According to a large scale and highly integrated semiconductor device in recent years, a design rule of wirings is also miniaturized in accordance with generation. Conventionally, the wirings are formed by performing a patterning of a conductive material by using lithography and dry etching after the conductive material is deposited on an insulating film. However, a technical limit begins to occur as the generation proceeds. Accordingly, a method so-called a damascene wiring in which wiring trenches and connection holes are formed at the insulating film, and thereafter, a wiring material is embedded in the wiring trenches and the connection holes to form the wiring structure is used as a new formation process of wiring taking over the conventional formation process. It is easy for the damascene process to form a wiring layer by using a low-resistance conductive material such as copper which is difficult to perform the dry etching, and it is extremely effective to form a fine and low-resistance wiring structure.
There are a single damascene method in which the wiring trenches and the connection holes are embedded separately with the conductive material, and a dual damascene method in which the wiring trenches and the connection holes (via holes) are simultaneously embedded with the conductive material in the damascene wiring. Between them, the embedding of the conductive material to the wiring trenches and the via holes is performed by one time process in the dual damascene method, and therefore, there is an advantage in which a manufacturing method is simplified compared to the single damascene method.
In the dual damascene method, there are a via-first method (refer to Patent Document 1) forming the via holes first and a trench-first method (refer to Patent Document 2) forming the wiring trenches first.
In the dual damascene method, problems such that a diameter of the via hole becomes small, and a leakage current occurs between adjacent wirings occur if a positional displacement between the via holes and the wiring trenches occurs when the via holes and the wiring trenches are formed.    Patent Document 1: Japanese Laid-open Patent Publication No. 11-274299    Patent Document 2: Japanese Laid-open Patent Publication No. 11-186274